I was wondering how you might go about doing a random approach. What to bring up, things to say, how to act?

I found that I have a lot of AA when it comes to just randomley approaching some girl compared to a more structured meeting (like meetup.com).

I went to a meetup event recently and number closed on some girl, though she wasn't really a HB (very cute face, potential to be a 8-9, but is currently overweight). I found myself not being that self-conscious there because we were suppose to meet and socialize.

Or am I missing something?